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Cooking&WashingEvaporation&BurningCausticizingTheDURALYZER-NIR Series of Liquor Analyzers for Alkali Based Pulping and RecoveryBLACK LIQUOR- Residual NaOH- Residual Na2S- Lignin- Other organicsWHITE LIQUOR- NaOH- Na2S- Na2CO3- Dead LoadGREEN LIQUOR- Na2CO3- Na2S- NaOH- Dead LoadREHR. E. Hodges, LLCPioneering Advanced Measurement Solutions for the Process IndustriesForwardWelcome to R. E. Hodges, LLCs catalog of measurement and control solutions for pulping and recovery processes. We take great pride in the innovation and quality of our products and the continuing service and support that we provide with each product. This catalog represents another effort to provide a tool to aid our customers in understanding our products and the technology that these products are based on. We are unique in our ability to work with the customer to customize a measurement solution to fit the exact needs of the customer. We provide a degree of expertise unmatched in the industry to create measurement solutions with unprecedented reliability, simplicity and accuracy. It is our goal to continually improve our products, our capabilities and our service and support to meet the challenges of our customerstechnological requirements. We firmly believe in the idea that our customers success translates into our success.In spite of our best efforts, this catalog is not perfect. We welcome any recommendations or suggestions that would help to improve the quality and utility of this literature.Thank YouTHE PEOPLE OF R. E. Hodges, LLCR. E. Hodges, LLC2217 Pumphrey AveAuburn, AL 36832Phone: (334)466-0057FAX: (334)466-0058e-mail: [email protected]:http://www.rehodges.comTechnical Data DisclaimerThe information given herein, includes drawings, illustrations and schematics (that are intended for illustration purposes only), is believed to be reliable. However, R. E. Hodges, LLC makes no warranties as to its accuracy or completeness and disclaims any liability in connection with its use. R. E. Hodges, LLCs only obligation shall be as set forth in R. E. Hodges, LLCs standard terms and conditions of sale for this product and in no way will R. E. Hodges, LLC be liable for any incidental, indirect or consequential damages arising out of the use or misuse of the product. Users of R. E. Hodges, LLCs products should make their own evaluation to determine the suitability of each such product for the specific application.REHCompany ProfileR. E. Hodges, LLC was founded in 2001 as a manufacturer of spectroscopic based measurement and control solutions for the process industries. Spectroscopic based measurement solutions hold the key to solving most if not all of the difficult measurement applications in the process industries. R. E. Hodges, LLC was formed to develop these measurement and control solutions so traditional lab based testing for quality control can be replaced by real time online measurements coupled with advanced control methods. R. E. Hodges, LLC is unique compared to traditional spectrometer manufactures in the fact that we provide turnkey measurement and control solutions, based on spectroscopic methods, that have been tailored to suit the application. When an analyzer leaves our manufacturing facility it has been optimized for the application and is guaranteed to have minimal installation requirements and minimal continuing maintenance requirements. We are so confident in our products that we include a complete money back guarantee if the customer is not totally satisfied with the performance of the product.ContentsThe Technology of Spectroscopy .....2Introduction .....................................................2Sample Analysis .............................................3The Beer-Lambert Relation ............................3Converting Spectral Data to ChemicalData ................................................................4The DURALYZER Approach .....................6Introduction .....................................................6DURALYZER-NIRArchitecture ..............................6DURALYZER-NIRInstallation Requirements.........7DURALYZER-NIR Analyzer Footprints...................8DURALYZER-NIRMaintenance Requirements ...10Definitions Of Acronyms...............................10Lab Based Liquor Analyzers ............11Introduction .................................................11Application Details.......................................11DURALYZER-NIR .vs. current solutions ............11Online Liquor Analyzers ...................13White liquor analyzer ................................13Introduction ..............................................13Application details ....................................13DURALYZER-NIR .vs. current solutions...........13Green liquor analyzer.................................15Introduction...............................................15Application details.....................................15DURALYZER-NIR .vs. current solutions...........15Dissolving/stabilization tank analyzer......18Introduction...............................................18Application details.....................................18DURALYZER-NIR .vs. current solutions...........18Causticizing analyzer..................................21Introduction...............................................21Application details.....................................21DURALYZER-NIR.vs. current solutions...........21Continuous digester analyzer....................24Introduction...............................................24Application details.....................................24DURALYZER-NIR .vs. current solutions...........24Batch digester analyzer...............................27Introduction...............................................27Application details.....................................27DURALYZER-NIR .vs. current solutions...........27Page 1REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057The Technology of SpectroscopyIntroductionChemical composition of process liquors is determined through the use of near-infrared (NIR) spectroscopy. This spectroscopic technique is a subset of a larger class of analytical techniques that fall in the category of optical spectroscopy techniques. The following figure shows the electromagnetic spectrum with the portion relating to optical spectroscopy expanded. Optical spectroscopy techniques have been used quite successfully for decades in the laboratory setting to analyze liquids, solids and gases composedof a multitude of chemical species. In the past twenty five years the development of miniaturized and durable electronic and optical components has allowed many of these techniques to be moved from the laboratory setting to the process environment. Development of new computational techniques along with the microcomputers to implement them have further advanced the use of spectroscopic techniques for both qualitative and quantitative analysis at the process.The Electromagnetic SpectrumCosmic-Rays -Rays X-RaysUVVis.InfraredMicrowavesUHFRadioWavelength (m)OpticalSpectroscopyWavelength (m)Wavelength (cm-1)VacuumUVFarUVNearUVVisibleLight100,00050,00030,00025,00020,00013,30012,5009,1004,0002,5002500.1 0.2 0.3 0.4 0.5 0.75 0.8 1.1 2.5 4 40Short WaveNear InfraredNearInfraredMidInfrared10-1310-12 10-1110-10 10-910-8 10-710-6 10-5 10-410-310-2 10-1 100 101 102103104Near infrared (NIR) spectroscopy has many attractive features that make it ideally suited for process analysis (refer to the previous figure to see the NIR portion of the electromagnetic spectrum highlighted in red). Some of the key features of this technique include minimal sample preparation, remote sensing through the use of fiber optic cables and simple implementation using relatively inexpensive and highly robust components. In addition, a wide variety of optical attachments are available to interface NIR spectrometers to the sample under test. NIR spectroscopy has been successfully implemented in the agricultural industry for grain analysis, the pharmaceutical industry for raw material and final product quality control and analysis, and the dairy industry for milk and butter analysis. Other process industries that have had successful NIR applications include petrochemical, food and beverage, polymers and specialty chemicals. These applications are a testament to the utility of NIR spectroscopy as a general purpose process sensor. Many other applications are currently under development in all of the process industries based on NIR spectroscopy as the primary analytical technology.Page 2REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057The Technology of SpectroscopySample AnalysisAs mentioned previously there are a wide variety of optical attachments available to interface an NIR spectrometer to a sample for gathering spectral information about the sample. The most common attachment used for liquid analysis is a transmission cell. The following figure shows this arrangement.Fiber OpticCable toSpectrometerQuartz Tungsten Halogen (QTH)NIR Light SourceLiquidSampleInletLiquid SampleOutletOpticalCouplerNIRLightTransmission CellCellBodyThe transmission cell provides a means for NIR radiation to interact with the process sample while isolating the light source, fiber optic cable and spectrometer from the process. A typical transmission cell is composed of a body with appropriate sample inlet and outlet connections and a pair of optical couplers to deliver light to the sample and collect light after interaction with the sample. The optical couplers house a set of lenses to focus the radiation onto the tip of the fiber optic cable. The ends of the couplers in contact with the process sample have windows, usually sapphire, to provide a transparent optical path for the entering and exiting light as well as providing isolation from the process sample. Sapphire is usually the material of choice for the coupler windows due to its combination of hardness, chemical and heat resistance and transparency over a broad range of wavelengths.The Beer-Lambert RelationLight interacts with the sample in accordance with the Beer-Lambert relation. The details of this relation can be seen in the figure on the following page. According to this relation light intensity decays exponentially as it travels through the material. The rate of decay depends on the concentrations of the constituent species of the material and their corresponding absorption coefficients. The total amount of decaydepends on the length of material the light crosses. The equation describing this phenomenon is highlighted in blue on the following page. Total absorption at a particular wavelength can be computed by applying a logarithm to this equation. The resulting equation is highlighted in red. The key observation to be made from this equation is that Absorption at a particular wavelength varies linearly with the concentrations of the constituent species. The path length, L, is fixed by the transmission cell, the absorption coefficients, ik, depend only on the wavelength i and the molecular structure of species k of the material under test, therefore the Absorption will change only when theconcentrations of the constituent species change. Another important observation to be made from the Absorption equation is that the Absorption at a particular wavelength depends on the concentration of ALL of the species that make up the sample under test. This is a major drawback for single wavelength instruments that are used to analyze multi-component materials. With these instruments the best that can be done is to select an observation wavelength that is highly absorbed by the component of interest while simultaneously minimizing the absorption of the other components. Page 3REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057The Technology of SpectroscopyMany times such a wavelength does not exist. This is an analogous situation to the application of conductivity for measuring effective alkali (EA) levels in white liquors. The white liquor conductivity is affected the most by the white liquor EA concentration but the sulfide and carbonate levels also have an affect on the conductivity. As a result, periodic recalibration of the conductivity meter is required to compensate for the effects of changing sulfide and carbonate levels.Converting Spectral Data to Chemical DataExtraction of physical and chemical information from spectral data can be achieved through a number of regression techniques. The field of chemometrics has provided a number of mathematical techniques to deal with this issue. One of the most popular techniques in use for relating spectral data to physical and chemical data is partial least squares regression (PLSR). This technique takes a set of spectral data derived from samples with known properties (e.g. EA, AA, TTA, etc.) and builds a regression model. This regression model can then be used with spectra from unknown samples to predict the chemical/physical properties of the unknown. The figure on the following page shows a graphic summarizing the calibration and prediction operations. In general a spectrum will have many more independent variables than available known samples which precludes the use of a standard regression approach. PLS reduces the size of the calibration spectral data set by computing a set of principal components. Any spectrum in the original data set can then be reproduced as some linear combination of these principal components. The principal components (PCs) are computed in such a way that a small number of PCs can be used to reproduce any given spectrum to any degree of precision desired. The original spectral data set is thus reduced to a small number of PCs and the corresponding coefficients required to reproduce each spectrum. Since the PCs are fixed for a given calibration set the coefficients now become the independent variables and represent the information content of the corresponding spectrum. At this point a standard regression model can be computed relating the spectral data to the properties of interest for the sample and the calibration is done. To predict an unknown sample a new spectrum is decomposed using the PCs from the calibration set. The information content of the new spectrum is reduced to a small number of coefficients based on the PCs from the calibration set. These coefficients are passed through the regression model to generate estimates of the desired physical/chemical properties of the sample.LI0(i) I(i)Material Under TestC1, C2, ... CNi1,i2...iNI0(i) - Entering light intensity for wavelength iI(i) - Exiting light intensity for wavelength iC1, C2, ... CN- Concentration of species 1, 2, ... NBeer-Lambert RelationNIR Light or any other light(e.g. UV, Vis., IR, etc.)i1,i2...iN- Absorption coefficients for species 1, 2, ... N for wavelength iL - Path length of sampleI(i) = I0(i)e-(ikCk)LNkI(i)/I0(i) = e-(ikCk)LNkA(i) - Total absorption for wavelength iA(i) = -ln[I(i)/I0(i) ] = (ikCk)LkNPage 4REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057The Technology of SpectroscopyPrincipal Components Calibration SpectraRegressionModelUnknown SpectrumCalibration PredictionChemical/Physical Property EstimatesPartial Least Squares Regression (PLSR)In A NutshellThe above figure summarizes the PLSR technique for extracting quantitative data from spectral data. A set of known test samples are used to generate calibration spectra. The calibration spectra are reduced to a much smaller set of template spectra that can be used to reproduce any spectra in the original set through aweighted sum of the template spectra. The template spectra are fixed for a given calibration set so the weights or coefficients used for each calibration spectra contain all of the information contained in the original spectrum. Usually 10 or less template spectra are all that is required to reproduce the original calibration set to within measurement noise limits. A regression model can then be computed based on the coefficients instead of the original spectra. When the spectrum of an unknown sample is acquired the required coefficients are calculated to reproduce the unknown spectrum using the template spectra. These coefficients are then passed throughthe regression model to give a prediction of the chemical/physical properties of the unknown sample.Page 5REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057The DURALYZER ApproachIntroductionThe DURALYZER-NIR series of liquor analyzers are like no other liquor analyzer solutions currently available. They represent a new generation of process liquor analyzers for alkali based chemical and semi-chemical pulping and recovery processes. These analyzers are the culmination of many years of research and development effort in both the laboratory and in the field, which has resulted in a family of systems with unprecedented reliability, accuracy and simplicity. These systems represent a comprehensive and highly cost effective solution to automated and manual liquor analysis.These analyzers define a new industry standard for liquor analysis systems that will become the final solution for these measurement applications.DURALYZER-NIR ArchitectureAll automated systems use process sample extraction technology coupled with near-infrared (NIR) spectroscopy for sample analysis. As a result of this design, all analyzers share a common technology platform. This common technology platform has been engineered into a set of highly integrated, completely self-contained analyzers with the lowest maintenance requirements ever achieved for these applications. The following figure shows the general hardware arrangement for these analyzers. SampleMultiplexing &ConditioningAcid CleaningSystem &Sampling OpticsNear-infrared (NIR)SpectrometerSample line 1Mill Water Mill Power Instrument AirAnalysis Results(4-20 mA outputs or MODBUS output)Sample ReturnTo ProcessSample line nLiquor Analyzer Functional Block DiagramSample line 2Electronics & PneumaticsPage 6REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057The DURALYZER ApproachDURALYZER-NIRArchitecture (Continued)Each analyzer is divided into four functional blocks which results in a highly modular and reliable design. Each block is physically isolated from the other by individual cabinets. Following is a brief description of each block with the function that is served.Sample Multiplexing & Conditioning - This portion of the analyzer is composed of valves and peripheralhardware required to reliably deliver process samples to the analyzer for analysis.Acid Cleaning System & Sampling Optics - This portion of the analyzer is composed of the optical hardwarerequired to interface the spectrometer to the sample under analysis. Additionally, an automated acid basedcleaning system keeps the sampling optics free from scale buildup.Electronics & Pneumatics - This portion of the analyzer houses the electronic and pneumatic hardware requiredto interface the spectrometer to the sample multiplexing & conditioning and acid cleaning systems. IO pointhardware and connections are also housed in this portion of the analyzer.Near-infrared (NIR) Spectrometer - The NIR spectrometer is the brains of the system. This device controls allaspects of sample extraction and preparation as well as the acid cleaning system. The spectrometer alsoanalyzes the sample for chemical composition and then makes the results readily available through industrystandard IO.DURALYZER-NIRInstallation RequirementsThe DURALYZER-NIR series of liquor analyzers has been designed to simplify installation and minimize installation costs. Each analyzer is delivered with all components mounted ona rollable stainless steel frame. This arrangement yields a portable analyzer that can be easily moved to other installation locations if the need arises. The small footprint of the system allows for many options in terms of installation location. There are currently two analyzer footprints depending on the application. Pictures and dimensions of these two footprints are shown on the following two pages. The spectrometer is thermally stabilized using a vortex cooling system. Cool air from this system is fed to the other cabinets through the conduit connections providing a slight positive pressure within these cabinets. This guarantees that all system cabinets stay dry and clean inside. The result of this arrangement is that the analyzerdoes not have any special housing requirements, as compared to titration based systems, and can be installed close to the process sample points. Utility requirements for these analyzers are straightforward. Most analyzer models can run from a common 120V-60Hz single phase 15A service with line, neutral and ground connections. Some models requiring the high pressure backflush system will also need a 230V or 480V-3 phase 10A service. Instrument air is also needed for the cooling system and valve actuators. Required air pressure can range from65-120 psi delivered in 1/2tubing or larger. Mill water is also needed for sample line backflushingand spectrometer referencing. Mill water needs to be available at 40 psi or higher with 100 ppmor less of total suspended solids. If mill water quality is an issue, samples can be sent to our facility for evaluation. In some cases potable water may be needed for spectrometer referencing.Sample line requirements vary depending on the application. Existing sample lines can be used in most cases, further reducing installation costs for the analyzer. Our technical department can provide sample line requirement details for a particular analyzer model to minimize installation costs.Page 7REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057The DURALYZER ApproachFootprint 1:White/Green liquor analyzer & Dissolving/stab. tank analyzer configurationElectronics & PneumaticsSample Multiplexing/Conditioning &Acid wash system/sampling opticsAcid ReservoirSpectrometerDimensions: Footprint 1 Length x Width x Height - 52x 32x 48Weight: Footprint 1270 - 320 lbs depending on configurationPage 8REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057The DURALYZER ApproachFootprint 2:Causticizing analyzer & Digester analyzer configurationAcid wash system & sampling opticsElectronics & PneumaticsSpectrometerSample Multiplexing &ConditioningAcid ReservoirPressure Booster PumpDimensions: Footprint 2 Length x Width x Height - 72x 32x 60Weight: Footprint 1420 - 485 lbs depending on configurationPage 9REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057The DURALYZER ApproachDURALYZER-NIRMaintenance RequirementsThe DURALYZER-NIR series of liquor analyzers has been designed to minimize short term and long term maintenancerequirements thus minimizing the cost of ownership. Scheduled maintenance requirements have been reduced to yearly bulb replacement in the light source and refreshing the optics cleaning acid on a one to six month schedule depending on the rate of scale buildup. Unscheduled maintenance has been greatly reduced by minimizing system component count as well as designing and implementing proprietary valves with a very high cycle life compared to off the shelf valves. A comprehensive set of alarm codes are available from the analyzer that will alert operators of any abnormal operation of the analyzer. In addition, a windows baseddiagnostics software package is provided that allows monitoring and testing of the analyzer through a TCP/IP ethernet connection from any PC on the network. All that is required is to assign the analyzer a TCP/IP address on the company intranet.Remote dialup is also available for the analyzer. A dedicated phone line connection is highly recommended forany of the online analyzers so our technicians can call in and quickly diagnose any problems that may not be apparent to mill personnel. Periodic call-ins are made into the analyzers by our technicians to verify operation of the analyzer and alert mill personnel of any pending issues that need to be addressed. The dial up connection also allows us to update software, calibrations and operational aspects of the analyzer if the need arises.Maintenance kits are available for all of the analyzers. These kits include burn in tested light sources, pneumatic actuator solenoids and solid state relays. Valve replacements can be purchased as separate items. Except for the proprietary sample valves, all other sampling system components are off the shelf items. Definitions Of AcronymsIn the pages that follow, detailed information for each analyzer application is presented. The following list of acronymsalong with their definitions are used in the description of the liquor chemistry.NaOH - Sodium HydroxideNa2S - Sodium SulfideNa2CO3- Sodium CarbonateNa2SO4- Sodium SulfateNa2SO3- Sodium SulfiteNa2S2O3- Sodium ThiosulfateCl-- Chloride IonEA Effective alkali (NaOH +Na2S)AA Active alkali (NaOH +Na2S)TTA Total titrateable alkali (NaOH +Na2S +Na2CO3)REA Residual effective alkali (residual NaOH +residual Na2S)RAA Residual active alkali (residual NaOH +residual Na2S)TDS Total dissolved solids 100% * (Mass of dry solids/Mass of liquor)TDD Total dissolved deadload100% * (Mass of (Na2SO4+Na2SO3+Na2S2O3+Cl-)/TDS)CE Causticizingefficiency 100% * (NaOH/(NaOH +Na2CO3))RE Reduction efficiency 100%* (Na2S/(Na2S +Na2SO4))Page 10REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057Lab Based Liquor AnalyzersIntroductionManual liquor testing has to be performed routinely for quality control purposes. Even if a mill has an online analyzer, periodic testing is still required to validate the online system. More often than not lab testing is the only measurement procedure available for process control decisions. The tedious and cumbersome nature of the standard ABC titration test for white, green and black liquors does not lend itself well to rapid manual testing. However, the nature of this testing procedure does lend itself well to induced errors if it is not performed with care and attention. As a result, liquor testing frequency is low and potentially biased and is usually performed at most once or twice per shift. The result of this practice is that much of the process variation is missed as well as the opportunity to reduce process variations. TheDURALYZER-NIR bench top analyzer has been designed to overcome all of the issues associated with manual liquor testing, providing fast, reliable and accurate results with minimal operator involvement. The DURALYZER-NIR bench top analyzer provides the results of the standard ABC titration test, providing effective alkali (EA), active alkali (AA) and total titrateable alkali (TTA) measurements for white and green liquors. In addition, total dissolved solids(TDS)andtotaldissolveddeadload (TDD)measurementsarealsoprovided.Forblackliquors,residual effectivealkali(REA),residualactivealkali(RAA),ligninand blackliquorTDSmeasurementsareprovided.The DURALYZER-NIR bench top analyzer uses the same NIR technology that is used in our online analyzers. This instrument has been designed specifically for the somewhat harsh lab environments of the pulping and recovery areas providing many years of trouble free operation. The only required maintenance for the instrument is an annual replacement of the light source and occasional acid cleaning of the sample cuvettes. Application DetailsCurrently three lab based analyzers are available. The only difference in the three instruments is in the preloaded calibrations. The three configurations available are as follows:1) Dissolving tank area analyzer calibrated for green liquor and weak wash analysis.2) Causticizing area analyzer calibrated for green liquor and white liquor analysis.3) Digester area analyzer calibrated for white liquor and black liquor analysis.All analyzers have a graphic touch screen setup for one button analysis once the sample is loaded. Test results are displayed on the screen and are printed out on the accompanying thermal printer. An optional IO module is available to write the results directly to the DCS through standard 4-20mA outputs or through a MODBUS connection.DURALYZER-NIR .vs. Current SolutionsThestandardABCtitrationtestrequiresmultiplechemicalsandlabequipmenttoimplement.Titrationchemicals suchascertifiedhydrochloricacidsolution,formaldehyde,bariumchlorideandvariouscolorindicatorsare inconvenient and costly to maintain in the process testing lab. If a pH probe is used to monitor the titration then pH standardsmustalsobekeptonhandtocalibratetheprobe.Inadditiontothechemicalrequirements,precision volume measurement equipment for the sample and titration acid must bemaintainedin goodworking order and periodicallycalibrated.Benchtoptitraters havebeenimplementedtoautomatetheactualtitrationtest.However, most of the same issues associated with the manual test are also present with the bench top titrater. At a minimum, titration acid and pH standards as well as precision volume measuring equipment are still needed for the bench top titrater.Mostbenchtoptitraters arebasedontheSCANtitrationmethod.ThismethoddiffersfromtheTAPPI standard ABC titration test in that formaldehyde and barium chloride are not used. Instead, a pH curve is generated as a function of the added titration acid. Inflection points on the titration curve are used to estimate the EA, AA and TTA values of the liquor sample. This technique can suffer from difficult to locate inflection points, especially for the AApoint.Theinflectionpointlocationscanvarywithvaryingdeadload concentrations,leadingtoerroneous concentration estimates. This effect is especially pronounced on the AA inflection point. The DURALYZER-NIR bench top analyzercompletelyeliminatesallofthenegativeissuesassociatedwithmanualandautomatedtitrationsby eliminatingthechemicalrequirements,accuratevolumemeasurementrequirementsandtheeffectsofdeadloadvariations. A table detailingthe primary advantages oftheDURALYZER-NIR benchtop analyzercomparedtocurrent practices is given on the following page along with a picture of the bench top unit.Page 11REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057Lab Based Liquor AnalyzersCharacteristic Titration Methods DURALYZER-NIR Bench Top AnalyzerAvailable Measurements3 - EA, AA, TTA 6 - EA, AA, TTA, TDS, TDD, LigninMeasurementTechniqueInferred Inflection pointmethod based on pH titra-tion curve(1)Inferred PLS regression technique based onTAPPI test methods (Regression model relatingspectral signature to chemical composition)MaintenanceHigh Replacement chem-icals, pH probe calibration,premature titrater failure(3)Very Low Yearly light source replacement, occasional lab validationMeasurementAccuracyPotential operator bias dueto volume errors. Manyopportunities to introduceerrorsAll operator bias removed since an accuratevolume of sample is not needed. Almost noopportunities for induced errors.Analysis Speed Slow Minutes(2)Fast 20 secondsDURALYZER-NIR Bench Top Analyzer .vs. Titration Methods1. SCAN titration method. More sensitive to deadloadvariations than standard TAPPI ABC testmethod.2. Analysis speeds vary greatly from several minutes for bench top titraters to tens of minutes fora full manual ABC test.3. Current commercial bench top titraters do not hold up well in the somewhat harsh process labenvironment.Page 12REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057Online Liquor AnalyzersWhite Liquor AnalyzerIntroductionReliable and accurate white liquor analysis for batch and continuous digesters is important for minimizing pulp quality variations. For both continuous and batch digesters white liquor composition needs to be accurately known to ensure that the correct effective alkali is charged for the given chip mass entering the digester. The two primary sources of variation that interfere with charging the correct amount of alkali on wood for batch and continuous digesters are chip moisture variations and white liquor variations. If white liquor composition is accurately known then one source of variation can be eliminated. With an online white liquor analyzer the white liquor can be trimmed in real time to meet target effective alkali and sulfidity levels allowing one to maintain a constant liquor to wood (L/W) ratio for a given alkali to wood ratio. Alternatively, variations in alkali to wood ratio induced by white liquor composition variations can be compensated for by only adjusting the liquor to wood ratio. Either approach requires an accurate online analysis of the cooking white liquor. The DURALYZER-NIR white liquor analyzer provides the required effective alkali (EA) and sulfidity measurements in a timely, accurate and reliable manner. Additionally, white liquor TTA, TDS and deadloadlevels are also available from the same analyzer.Application DetailsThegraphiconthefollowingpageshowshowthe DURALYZER-NIR whiteliquoranalyzercanbeimplementedfor monitoringandcontrollingthewhiteliquorchargetoeitherbatchorcontinuousdigesters.Twopossible configurations are given in the graphic. The white liquor trim tank configuration adjusts white liquor composition to a preset level so a constant liquor to wood (L/W) ratio can be maintained for a set alkali to wood ratio. The second configuration monitors white liquor composition without any means for adjusting the white liquor. This configuration requires that the alkali to wood ratio has to be adjusted by varying the liquor to wood (L/W) ratio. The goal of both configurations is to charge the correct amount of alkali for the given amount of chip mass in the digester. The trim tankconfigurationhastheaddedadvantageofallowingadjustmentstowhiteliquorsulfidity aswellasEA,thus providing a means for incremental yield adjustments based on the cooking liquor composition.DURALYZER-NIR .vs. Current SolutionsThe current online sensor of choice for this application is the conductivity meter. Automated titration is an option as well but tends to be cost prohibitive. More often than not manual testing is the primary white liquor analysis method. This is primarily due to the fact that conductivity is a single point measurement and as such is only an indication of white liquor effective alkali. However, conductivity is also sensitive to variations in white liquor sulfidity, carbonate andotherdead-loadionicspeciesaswell.Variationsinthesecomponentsrequireperiodicmanualtestingto compensate for these variations within the instrument. The result is that the conductivity meter is recalibrated after each manual test to minimize this induced drift. If a sudden change in sulfidity or carbonate levels is experienced between manual tests the conductivity meter will report an incorrect effective alkali level in the white liquor, leading to anincorrectwhiteliquorchargeintothedigester.TheDURALYZER-NIR analyzereliminatesthisissuesincesulfide, carbonate and dead-load levels are directly measured alongwiththe effective alkali.The DURALYZER-NIR analyzer allows the mill to drastically reduce manual testing of white liquor by operators to a weekly or monthly activity. With manual testing reduced to this level the analyzer can be validated by the mills main lab to eliminate operator bias in this testing procedure. A table detailing the primary advantages of the DURALYZER-NIR white liquor analyzer compared to current practices is given on the following page.Page 13REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057Online Liquor AnalyzersWhite Liquor AnalyzerWhiteLiquorStorageTankWhiteLiquorTrimTankDURALYZER-NIRWhite Liquor AnalyzerPurchased NaSHPurchased NaOHFrom WL StorageTo DigesterTo DigesterORConstant L/WConfigurationVarying L/WConfigurationSample ReturnSample ReturnSample LineSample LineDURALYZER-NIR White Liquor Analyzer ImplementationPage 14REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057Characteristic Conductivity Meter DURALYZER-NIR White Liquor AnalyzerAvailable Measurements1 - WL - EA 6 - WL - EA, AA, TTA, TDS, TDD, TSSMeasurementTechniqueInferred Solutionconductivity correlated to WL - EAInferred PLS regression technique based onTAPPI test methods (Regression model relatingspectral signature to chemical composition)Maintenance -AnalyzerHigh Constant recalibration, potentialscale buildup issuesVery Low Yearly light source replacement, occasional lab validationMaintenance -Sampling SystemN/AVery Low 1 - 2 year valve servicing, 1-6 monthcleaning acid replacementAnalysis Speed Fast Continuous update Moderate Three minute update cycleTotal InstalledCostLow Low - ModerateDURALYZER-NIR White Liquor Analyzer .vs. ConductivityOnline Liquor AnalyzersGreen Liquor AnalyzerIntroductionReliable and accurate greenliquor analysisforthe slakingprocessisimportantfor optimizinglime usage.Green liquor sodium carbonate (Na2CO3) levels need to be accurately known to ensure the correct amount of lime is dosed for the incoming green liquor. The two primary sources of variation that interfere with dosing the correct amount of lime on green liquor are lime quality variations and green liquor carbonate variations. If the green liquor composition is accurately known then one source of variation can be eliminated. With an online green liquor analyzer the green liquorcanbetrimmedinrealtimetomeettargettotaltitrateable alkali(TTA)orNa2CO3levelsallowingoneto maintain a lime feed rate that depends only on green liquor throughput leading to reduced variations in lime screw speed. Alternatively, variations in green liquor composition can be used along with green liquor flow rate to determine the required lime dosing. Either approach requires an accurate online analysis of the green liquor entering the slaker. The DURALYZER-NIR green liquor analyzer provides the required active alkali (AA) and TTA measurements in a timely, accurate and reliable manner. Additionally, green liquor effective alkali (EA), total dissolved solids (TDS) and total dissolved dead-load (TDD) levels are also available from the same analyzer.Application DetailsThegraphiconthefollowingpageshowshowthe DURALYZER-NIR greenliquoranalyzercanbeimplementedfor monitoring and/or controlling the composition of the green liquor entering the slaker. Two possible configurations are given in the graphic. The varying TTA or Na2CO3configuration monitors the green liquor composition and uses these measurementsalongwithgreenliquorflowratetodeterminetheappropriateamountoflimetobedosed.The second configuration provides a means by which the green liquor TTA or Na2CO3levels can be trimmed using weak wash to achieve a constant green liquor composition so that lime dosing into the slaker depends only on the green liquor throughput. The goal of both configurations is to dose the correct amount of lime on the green liquor entering the slaker.The constant TTA orNa2CO3configuration hasthe added advantage ofminimizinglimescrewspeed variations further reducing ware on process equipment. Note that these techniques provide a means of feed-forward control of the causticizing process and do not take lime quality variations into account. To implement a feed-forward feed-back control arrangement for the causticizing process look at the DURALYZER-NIR Causticizinganalyzer section.DURALYZER-NIR .vs. Current SolutionsThecurrentonlinesensorsofchoiceforthisapplicationaretherefractiveindex(RI)meteranddensitymeter. Automated titration is an option as well but tends to be cost prohibitive for a single sample line measurement. More oftenthannotmanualtestingistheprimarygreenliquoranalysismethod.Thisisprimarilyduetothefactthat implementing refractive index or density measurements at this location requires periodic removal and cleaning of the sensors to eliminate scale buildup. High pressure washing or steam cleaning has to be implemented along with the sensor to reduce this maintenance issue. The brute force approaches of these cleaning methods can lead to damage ofthesensorheadsrequiringunplannedmaintenance.Liketheconductivitymeasurement,refractiveindexand density are single point measurements and as such are only an indicator of green liquor TTA. Both approaches give a TDS estimate from which TTA is inferred. Neither approach can provide a direct sodium carbonate measurement. TheDURALYZER-NIR greenliquoranalyzereliminatesalloftheseissuesbyprovidingadirectTTAandAA measurement from which a direct sodium carbonate measurement can be obtained. The automated acid cleaning system that is standard on all DURALYZER-NIR models eliminates any scale buildup from the sensor head so the end user does not have to deal with manual cleaning or the design and maintenance of a brute force cleaning method. TheDURALYZER-NIR greenliquoranalyzerallowsthemilltodrasticallyreducemanualtestingofgreenliquorby operators to a weekly or monthly activity. With manual testing reduced to this level the analyzer can be validated by the mills main lab to eliminate operator bias in this testing procedure. A table detailing the primary advantages of the DURALYZER-NIR green liquor analyzer compared to current practices is given on the following page.Page 15REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057Online Liquor AnalyzersGreen Liquor AnalyzerGreen LiquorClarifierSlakerORDURALYZER-NIRGreen Liquor AnalyzerWeakWashGreen LiquorClarifierSlakerSample ReturnSample ReturnSample LineSample LineVarying TTA or Na2CO3Constant TTA or Na2CO3DURALYZER-NIR Green Liquor Analyzer ImplementationPage 16REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057Online Liquor AnalyzersGreen Liquor AnalyzerCharacteristicRefractometerDensity MeterDURALYZER-NIRGreeenLiquor AnalyzerAvailable Measurements1 -GL -TTA5 -GL -EA, AA, TTA, TDS, TDDMeasurementTechniqueInferred GL-Ref. Indexcorrelated to GL -TDS,correlated to GL -TTAInferred PLS regression technique based onTAPPI test methods (Regression model relatingspectral signature to chemical composition)Maintenance -AnalyzerHigh Manual cleaningor automated steam/high pressure wash(1)Very Low Yearly light source replacement, occasional lab validationMaintenance -Sampling SystemN/AVery Low (2)1 -2 year valve servicingAnalysis SpeedFast Continuous updateModerate Three minute update cycleTotal InstalledCostLow -ModerateDURALYZER-NIRGreen Liquor Analyzer .vs. Refractive Index & Density1 -GL -TTAInferred GL-Density correlated to GL -TDS, correlated to GL -TTAHigh Manual cleaningor automated steam/high pressure wash(1)N/AMeasurementResolutionGoodAverageExcellentLow -Moderate(3)Low -Moderate(3)Fast Continuous update1. Automated cleaning system is implemented by the mill. Brute force cleaning methods can lead to sensor head damage.2. Integrated acid cleaning system requires only that acid be refreshed every 1-6 months depending on level of scaling.Cleaning system has no adverse effects on sensor head.3. Total installed cost and operating cost can increase substantially depending on design and implementation of automatedcleaning system.Page 17REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057Online Liquor AnalyzersDissolving/Stabilization Tank AnalyzerIntroductionReliable and accurate liquor analysis at the dissolving tank and stabilization tank locations is key to controlling the quality of the green liquor that is sent to the causticizingprocess. Stabilizing the green liquor composition as much as possible at these locations ensure that variations in the down stream green liquor is minimized before reaching the recaust area.Stabilizationofthegreenliquoratthedissolvingtankisalsoimportantforcontrollingthesettling characteristics of the liquor and minimizing scale buildup in piping and process equipment. It is desirable to maintain green liquor TTA in as tight a range as possible; to high a TTA can lead to scaling issues, to low a TTA leads to reactivity issues at the slaker. With an online dissolving/stabilization tank analyzer the green liquor composition can be controlled in real time to meet target TTA or Na2CO3levels. In addition to the green liquor analysis provided by thisanalyzer,weakwashTTAisalsoprovidedallowingforafeedforward-feedbackcontrolarrangement.The DURALYZER-NIR dissolving/stabilization tank analyzer provides the required green liquor AA and TTA measurements in a timely, accurate and reliable manner for green liquor composition control. Additionally, green liquor EA, TDS, TDD and RE are also available from the same analyzer as well as the weak wash TTA measurement.Application DetailsThegraphiconthefollowingpageshowshowthe DURALYZER-NIR dissolving/stabilizationtankanalyzercanbe implemented for controlling the composition of the green liquor exiting these tanks. The graphic shows a two sample line arrangement; one line for green liquor the other for weak wash. The standard analyzer configuration comes with threesamplelines.Thisallowstheanalyzertoalsobeconnectedtothesparelinethatmostdissolvingtank arrangements are equipped with. A signal from the DCS or a PLC is used to communicate to the analyzer the current flow configuration (i.e. which isthe greenliquorline and whichistheweak washline).Afeedbackcontrol signal based on green liquor TTA or Na2CO3levels can then be used to adjust weak wash flow to maintain target TTA or Na2CO3levels. The combination green liquor analysis and weak wash analysis from the analyzer can be used for stabilizationtankstogettightcontroloverthegreenliquorcompositionusingafeedforward-feedbackcontrol arrangement. Dissolving tank analysis is unique among the liquor analysis applications due to the rapid step changes that can occur from smelt rush conditions. In addition, scaling at this location can also be a serious issue, quickly fouling other sensor solutions to a degree that makes them inoperable. The DURALYZER-NIR analyzer solves both of theseissues.Greenliquoranalysisresultscanbeprovidedinasshortatimeasathreeminutecycle. SpecialTeflonlinedsampletapsensurethatthetaplocationsdonotscaleuptoadegreethatwould interfere with collecting a valid process sample. DURALYZER-NIR .vs. Current SolutionsThecurrentonlinesensorsofchoiceforthisapplicationaretherefractiveindex(RI)meteranddensitymeter. Automated titration is an option as well but tends to be cost prohibitive. Slow analysis speed of automated titration is also a major drawback for this application. More often than not manual testing is the primary green liquor analysis method. This is primarily due to the fact that implementing refractive index or density measurements at this location requires periodic removal and cleaning of the sensors to eliminate scale buildup. High pressure washing or steam cleaning has to be implemented along with the sensor to reduce this maintenance issue. The brute force approaches ofthesecleaningmethodscanleadtodamageofthesensorheads requiringunplannedmaintenance.Likethe conductivitymeasurement,refractiveindexanddensityaresinglepointmeasurementsandassuchareonlyan indicator of green liquor TTA. Both approaches give a TDS estimate from which TTA is inferred. Neither approach canprovideadirectsodiumcarbonatemeasurement.TheDURALYZER-NIR dissolving/stabilizationtankanalyzer eliminates all of these issues by providing a direct TTA and AA measurement from which a direct sodium carbonate measurement can be obtained. The automated acid cleaning system that is standard on all DURALYZER-NIR models eliminates any scale buildup from the sensor head so the end user does not have to deal with manual cleaning or the design and maintenance of a brute force cleaning method. Page 18REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057Online Liquor AnalyzersDissolving/Stabilization Tank AnalyzerDURALYZER-NIR .vs. Current Solutions (Continued)The DURALYZER-NIR dissolving/stabilization tank analyzer allows the mill to drastically reduce manual testing of green liquor by operators to a weekly or monthly activity. With manual testing reduced to this level the analyzer can be validated by the mills main lab to eliminate operator bias in this testing procedure. A table detailing the primary advantages of the DURALYZER-NIR green liquor analyzer compared to current practices is given on the following page.Smelt Dissolving TankorStabilization TankTo GL ClarifierorSlakerWeakWashDURALYZER-NIRDissolving/StabilizationTank AnalyzerDURALYZER-NIR Dissolving/Stabilization Tank Analyzer ImplementationSample ReturnSample LineSample LinePage 19REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057Online Liquor AnalyzersDissolving/Stabilization Tank AnalyzerCharacteristicRefractometerDensity MeterDURALYZER-NIRGreeenLiquor AnalyzerAvailable Measurements1 -GL -TDS7 -GL -EA, AA, TTA, TDS, TDD, RE & WW -TTAMeasurementTechniqueInferred GL-Ref. Indexcorrelated to GL -TDS,correlated to GL -TTAInferred PLS regression technique based onTAPPI test methods (Regression model relatingspectral signature to chemical composition)Maintenance -AnalyzerHigh Manual cleaningor automated steam/high pressure wash(1)Very Low Yearly light source replacement, occasional lab validationMaintenance -Sampling SystemN/AVery Low (2)1 -2 year valve servicingAnalysis SpeedFast Continuous updateModerate Three minute update cycleTotal InstalledCostLow -ModerateDURALYZER-NIRDissolving/Stab. Tank Analyzer .vs. Refractive Index & Density1 -GL -TDSInferred GL-Density correlated to GL -TDS, correlated to GL -TTAHigh Manual cleaningor automated steam/high pressure wash(1)N/AMeasurementResolutionGoodAverageExcellentLow -Moderate(3)Low -Moderate(3)Fast Continuous update1. Automated cleaning system is implemented by the mill. Brute force cleaning methods can lead to sensor head damage.2. Integrated acid cleaning system requires only that acid be refreshed every 1-6 months depending on level of scaling.Cleaning system has no adverse effects on sensor head.3. Total installed cost and operating cost can increase substantially depending on design and implementation of automatedcleaning system.Page 20REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057Online Liquor AnalyzersCausticizing AnalyzerIntroductionReliableandaccuratewhiteandgreenliquoranalysisatkeylocationsinthecausticizing processisrequiredto produce a stable high quality supply of cooking white liquor. Variations in green liquor composition and variations in lime quality require an online measurement solution to optimize control of the causticizing process. Operating the process at the highest CE% possible without overliming is very difficult based on manual tests and delta-T control. Measurementsforgreenliquorcarbonatelevelsgoingintotheslaker andwhiteliquorcompositiondownstream provide the necessary information to compensate for the majority of the process variations that will be experienced in practice.Greenliquorcompositionmeasurementscomingintotheslaker providestheNa2CO3measurement necessaryforfeedforward controlofthelimescrewwhilewhiteliquorEAmeasurementsin theslaker and downstreamcausticizers providethefeedbackinformationrelatingtolimequalityvariations.Sinceallofthe component concentrations for each sample point is available fromthe analyzer, CE% can be computed directly. The DURALYZER-NIR analyzer solution easily provides these measurements in a timely and reliable manner. Additionally, TDS and TDD measurements are also available for each sample stream.Application DetailsThegraphiconthefollowingpageshowshowthe DURALYZER-NIR causticizing analyzercanbeimplementedfor feedforward-feedbackcontrolofthecausticizing process.Thestandardconfigurationforthisanalyzerisafoursample line arrangement. One sample line monitors the green liquor coming into the slaker, one line monitors the white liquor exiting the slaker or first causticizer, one line monitors the white liquor exiting a downstream causticizerand one line monitors the clarified white liquor. This arrangement gives the necessary green liquor and white liquor analysis needed for a feedforward-feedback control arrangement. Other configurations are possible supporting up to eight (8) sample lines. A specially designed vacuum system draws slurry samples from the slaker and causticizerseliminating the need for special pumps to deliver the sample from these locations to the analyzer. All samples flow from the process through the analyzer and directly back into the process.DURALYZER-NIR .vs. Current SolutionsThecurrentonlinesensorsofchoiceforthisapplicationareautomatedtitrater basedsolutionsanddifferential conductivity based solutions. Both of these solutions have a high total installed cost and a high longtermcost of ownership due to high maintenance demands for these systems. In addition, differential conductivity methods only provideaninferredCE%measurementsinceconductivitymetersaresinglepointinstrumentsasdescribedin previous sections. CE% is estimated using neural networks or some other nonlinear modeling method to provide an estimatebasedonconductivitydifferencesbetweendifferenttanksintheprocess.Conductivityprobesare distributed throughout the process and may require periodic removal and cleaning to deal with scale buildup issues. Titrater basedsolutionstendtobecomplicatedintheirimplementation. Adeionized watersystem,weekly replacementofstandardizedreagentgradehydrochloricacidsolutionandperiodicvalveanddiaphragmpump replacement all contribute to the high maintenance requirement for these systems. Special housing requirements for the titrater system contribute greatly to the total installed cost of this device. The DURALYZER-NIR causticizing analyzer eliminates all of these issues in one compact, cost effective, turnkey solution. The automated acid cleaning system that is standard on all DURALYZER-NIR models eliminates any scale buildup from the sensor head so the end user does nothavetodealwithmanualcleaning.Aminimizedhardwarearrangementbasedonproprietaryhighcyclelife valves and vacuum system ensurethatthe samplingsystem performswith nearzeromaintenancerequirements. ThevortexcoolingsystemandpackagingofDURALYZER-NIR analyzersallowthemtositinthemostconvenient location of the process area as delivered, greatly reducing installation costs and total installed cost. Additionally, EA, AA and TTA measurements are provided for each sample stream so that all causticizing process parameters can be directly calculated. A table detailing the primary advantages of the DURALYZER-NIR causticizing analyzer compared to current solutions is given on the following page. Page 21REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057Online Liquor AnalyzersCausticizing AnalyzerPage 22REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057SmeltDissolvingTankGreenLiquorClarifierSlakerCausticizersWeakWashWhiteLiquorClarifierSample LineSample LineSampleLineSample ReturnSample LineDURALYZER-NIRCausticizingAnalyzer ImplementationDURALYZER-NIRCausticizingAnalyzerOnline Liquor AnalyzersCausticizing AnalyzerCharacteristicAutotitraterDiff. ConductivityDURALYZER-NIRCausticizingAnalyzerAvailable Measurements3 -EA, AA, TTA(all streams)5 -EA, AA, TTA, TDS, TDD (all streams)MeasurementTechniqueInferred SCAN method (inflection point search ofpH titration curve)1Inferred PLS regression technique based onTAPPI test methods (Regression model relatingspectral signature to chemical composition)Maintenance -AnalyzerHigh Weekly acid replacement, pH probe calibration, deionizedwater system maintenanceVery Low Yearly light source replacement, occasional lab validationMaintenance -Sampling SystemHigh -6 month valvereplacement, periodicdiaphragm pumpreplacementVery Low (2)1 -2 year valve servicingAnalysis SpeedModerate Sample,settle and analyzecycleModerate/Fast Sample, fast settle and fast analyze cycleTotal InstalledCostLow -Moderate in comparisonDURALYZER-NIRCausticizingAnalyzer .vs. Titratersand Differential Conductivity1 -Inferred CE%Inferred CE% correlated to differential conductivityModerate/High -Periodicmanual cleaning ofprobesN/AComplexityHigh -Deionizedwater system, manymoving partsLow -multipleprobesModerate -mostly solid state deviceModerate -HighHigh -Special housing,requirements, special sample line requirementsFast Continuous update1. AA inflection point is sensitive to deadloadchanges, especially changes in Na2SO3, leading to erroneousresults in Na2S and Na2CO3 estimates.2. Integrated acid cleaning system requires only that acid be refreshed every 1-6 months depending on level of scaling.Page 23REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057Online Liquor AnalyzersContinuous Digester AnalyzerIntroductionMonitoring black liquor composition in a continuous digester provides a means for implementing advanced control schemes in the pulping process. The residual EA profile is an indicator of exiting pulp kappa number, the residual AA profile, lignin profile and TDS profile are indicators of exiting pulp yield. By monitoring and stabilizing these profiles in a continuous digester pulp quality variations can be greatly reduced while maintaining a maximum yield. Digesters runningstandardcookscancompensateforresidualEAvariations byadjustingthetemperaturesinthecooking zones. Variations in residual EA can also be compensated for by trimming the incoming white liquor or adjusting the liquor to wood ratio. Continuous digesters fitted with liquor feed points in the cooking zones have the added flexibility of accurately and quickly controlling the residual EA profile throughout the digester by directly injecting white liquor into these zones. Controlling the residual EA profile and cooking conditions in a continuous digester by either method requiresreliableandaccuratemeasurements.TheDURALYZER-NIR analyzersolutioneasilyprovidesthese measurements in atimely andreliable manner.Additionally,residual AA,lignin andTDSmeasurements are also available from the same analyzer. Black liquor composition contains a wealth of information relating to various pulp properties. The DURALYZER-NIR analyzer captures this information in the spectral signature of the black liquor sample. So in addition to providing the previously mentioned measurements, a variety of pulp properties (e.g. kappa number, relative yield and viscosity) can be directly correlated to the liquor spectral signature. Application DetailsThe graphic on the following page shows howthe DURALYZER-NIR continuous digester analyzer is implemented on aKamyr digesterrunningastandardkraft cook. Similar arrangementswould also applyforMCCandEMCC digesters. This implementation has six sample lines, monitoring the incoming white liquor, liquor return, upper and lower cooking zones, extraction zone and the incoming filtrate liquor. All samples flow from the process through the analyzer and directly back into the process. This arrangement gives a complete picture of the digestion process from the perspective of liquor composition variations. Other arrangements supporting different digester arrangements are available supporting up to eight (8) sample lines. Proprietary filters combined with a high pressure backflush system ensurethatlinepluggingduetochipdebrisdoesnotinterferewithsamplecollection.Proprietaryhighcyclelife valvesensurethatvalvemaintenanceisnotrequiredfortwoormoreyears.WhiteliquorEA,AA,TTA&TDS measurementsareprovidedforwhiteliquorandreturnliquorlines.BlackliquorREA,RAA,lignin&TDSare provided for all of the black liquor streams.DURALYZER-NIR .vs. Current SolutionsCurrentsensorsforthisapplicationincludehybridsystemscomposedofsomearrangementofarefractometer, conductivitymeterandUVabsorptionmeter.Onlinetitraters areanotheroptionforthisapplication.Titraters are limited to measuring only residual EA, however. A major drawback to these hybrid systems is that each meter has to be calibrated for the particular component that it will be measuring. Additionally, since this sensor is a collection of singlepointmeasurementsitissusceptibletothesamedriftissuesasconductivitymetersareforwhiteliquor analysis.Onlinetitraters canmeasureresidualEAusinganautomatedversionofthemanualresidualEAtest, however, this is usually the only measurement that is available. Maintenance requirements for an online titrater are alsoquitehighforthisapplication.Thecombinationoflimited measurementsandexcessivemaintenance requirements make it difficult to justify the capital investment for a titration based solution. The DURALYZER-NIR digester analyzer solution provides the collection of measurements that the hybrid sensor provides in one low maintenance, cost effective instrument. A table detailing the primary advantages of the DURALYZER-NIR continuous digester analyzer compared to current technologies is given on the following page.Page 24REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057Online Liquor AnalyzersContinuous Digester AnalyzerUpper/LowerCirculationExtractionWashCirculationDURALYZER-NIRContinuous Digester AnalyzerTop CirculationTop Circulation ReturnWhiteLiquorStorageChipBinPulp To WashersDURALYZER-NIRContinuous Digester Analyzer ImplementationSample ReturnSample LineSample LineSample LineSample LineSample LineSample LineToFlashTanksPage 25REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057Online Liquor AnalyzersContinuous Digester AnalyzerCharacteristicAutotitraterHybrid Systems DURALYZER-NIRDigester AnalyzerAvailable Measurements1 -BL -REA4 -WL -EA, AA, TTA, TDS4 -BL -REA, RAA, Lignin, TDSMeasurementTechniqueInferred SCAN method (inflection point search ofpH titration curve)Inferred PLS regression technique based onTAPPI test methods (Regression model relatingspectral signature to chemical composition)Maintenance -AnalyzerHigh Weekly acid replacement, pH probe calibration, deionizedwater system maintenanceVery Low Yearly light source replacement, occasional lab validationMaintenance -Sampling SystemHigh -6 month valvereplacementVery Low (2)1 -2 year valve servicingAnalysis SpeedModerate Sample,analyze cycleModerate/Fast Sample, fast analyze cycleTotal InstalledCostLow -Moderate in comparisonDURALYZER-NIRDigester Analyzer .vs. Autotitratersand Hybrid Systems3 -BL-REA, Lignin, TDSInferred RI for TDS,Conductivity for REA,UV Absorbance for ligninHigh -Periodic recali-brationof single pointinstrumentsComplexityHigh -Deionizedwater system, manymoving partsHigh -Multiple singlepoint instruments,dilution system for UVModerate -mostly solid state deviceModerate -HighHigh -Special housing,requirements, special sample line requirementsModerate Sample,analyze cycle1. AA inflection point is sensitive to deadloadchanges, especially changes in Na2SO3, leading to erroneousresults in Na2S and Na2CO3 estimates.2. Integrated acid cleaning system requires only that acid be refreshed every 1-6 months depending on level of scaling.High -6 month valvereplacementPage 26REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057Online Liquor AnalyzersBatch Digester AnalyzerIntroductionSimilar to the continuous digester, monitoring black liquor composition in a batch digester provides a means for implementing advanced control schemes in the pulping process. As in the continuous case, the residual EA profile is an indicator of exiting pulp kappa number, the residual AA profile, lignin profile and TDS profile are indicators of exiting pulp yield. The primary difference being that in the batch case these profiles are a function of time instead of space. These time varying profiles can be correlated to the average kappa and yield of the exiting pulp or a mass balance model can be used to directly calculate kappa and yield during the course of the cooking process.Monitoring of the EA profile during temperature ramp up allows the alkali to wood ratio to be trimmed prior to sealing the digester, resulting in a more consistent charge of cooking chemicals for each cook. Black liquor composition contains a wealth of information relating to various pulp properties. The DURALYZER-NIR analyzer captures this information in the spectral signature of the black liquor sample. So in addition to providing the previously mentioned measurements, a variety of pulp properties (e.g. kappa number, relative yield and viscosity) can be directly correlated to the liquor spectral signature. Whatever advanced batch digester control scheme is implemented requires reliable and accurate measurements. The DURALYZER-NIR analyzer solution easily provides these measurements in a timely and reliable manner. Application DetailsThe graphic on the following page shows howthe DURALYZER-NIR digester analyzer is implemented on batch digesters running a standard kraft cook. Each digester has a dedicated sample line supplying the analyzer.All samples flow from the process through the analyzer and directly back into the process. One analyzer can support up to eight different digesters. Proprietary filters combined with a high pressure backflush system ensure that line plugging due to chip debris does not interfere with sample collection. Proprietary high cycle life valves ensure that valve maintenance is not required for two or more years. Black liquor REA, RAA, lignin & TDS are provided for each connected digester.DURALYZER-NIR .vs. Current SolutionsCurrent sensors for this application are the same as for the continuous digester case and include hybrid systems composed of some arrangement of a refractometer, conductivity meter and UV absorption meter. Online titraters are another option for this application. Titraters are limited to measuring only residual EA, however. A major drawback to these hybrid systems is that each meter has to be calibrated for the particular component that it will be measuring. Additionally, since this sensor is a collection of single point measurements it is susceptible to the same drift issues as conductivity meters are for white liquor analysis. Online titraters can measure residual EA using an automated version of the manual residual EA test, however, this is usually the only measurement that is available. Maintenance requirements for an online titrater are also quite high for this application. The combination of limited measurements and excessive maintenance requirements make it difficult to justify the capital investment for a titration based solution. The DURALYZER-NIR digester analyzer solution provides the collection of measurements that the hybrid sensor provides in one low maintenance, cost effective instrument. A table detailing the primary advantages of the DURALYZER-NIR batch digester analyzer compared to current technologies is given on the following page.Page 27REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057Online Liquor AnalyzersBatch Digester AnalyzerPage 28REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057Sample ReturnDURALYZER-NIRBatch Digester AnalyzerTo BlowTankBlow LineSample LineSample LineSampleLineDURALYZER-NIRBatch Digester Analyzer ImplementationOnline Liquor AnalyzersBatch Digester AnalyzerCharacteristicAutotitraterHybrid Systems DURALYZER-NIRDigester AnalyzerAvailable Measurements1 -BL -REA4 -WL -EA, AA, TTA, TDS4 -BL -REA, RAA, Lignin, TDSMeasurementTechniqueInferred SCAN method (inflection point search ofpH titration curve)Inferred PLS regression technique based onTAPPI test methods (Regression model relatingspectral signature to chemical composition)Maintenance -AnalyzerHigh Weekly acid replacement, pH probe calibration, deionizedwater system maintenanceVery Low Yearly light source replacement, occasional lab validationMaintenance -Sampling SystemHigh -6 month valvereplacementVery Low (2)1 -2 year valve servicingAnalysis SpeedModerate Sample,analyze cycleModerate/Fast Sample, fast analyze cycleTotal InstalledCostLow -Moderate in comparisonDURALYZER-NIRDigester Analyzer .vs. Autoitratersand Hybrid Systems3 -BL-REA, Lignin, TDSInferred RI for TDS,Conductivity for REA,UV Absorbance for ligninHigh -Periodic recali-brationof single pointinstrumentsComplexityHigh -Deionizedwater system, manymoving partsHigh -Multiple singlepoint instruments,dilution system for UVModerate -mostly solid state deviceModerate -HighHigh -Special housing,requirements, special sample line requirementsModerate Sample,analyze cycle1. AA inflection point is sensitive to deadloadchanges, especially changes in Na2SO3, leading to erroneousresults in Na2S and Na2CO3 estimates.2. Integrated acid cleaning system requires only that acid be refreshed every 1-6 months depending on level of scaling.High -6 month valvereplacementPage 29REHR. E. Hodges, LLCWebsite: http://www.rehodges.comTelephone: (334)466-0057